1. Field of the Invention
The present invention relates to a mobile device having an ear jack interface. More particularly, the present invention relates to an earphone system and operation method thereof for identifying various input signals offered from an earphone connected to the ear jack interface and thereby for controlling a particular user-function in response to the identified signal.
2. Description of the Related Art
Normally, a mobile device denotes a type of electronic device that provides mobility and portability. With remarkable growth of related technologies, a great variety of mobile devices, such as a mobile communication device and a Personal Digital Assistant (PDA), are becoming increasingly popular these days. A typical mobile communication device has a module for supporting a mobile communication function and thereby allows voice and data communications with other mobile communication devices through a base station. A typical PDA has a Central Processing Unit (CPU), a memory unit, an Operating System (OS), and various programs and modules that operate based on the OS, and thereby allows various functions to collect, store, write and search information.
Some functions of the mobile device, e.g., a call function, an audio file play function, etc., inherently include a function to output audio signals through a speaker provided on the mobile device. Alternatively, a user of the mobile device may use an earphone to prevent sounds from being heard outside or to hear clearer sounds.
For a connection with an earphone, a conventional mobile device typically includes a 4-pole ear jack interface. However, this 4-pole ear jack interface only supports an audio signal output through right and left earphone speakers and an audio signal input through an earphone microphone. Additionally, the 4-pole ear jack interface merely recognizes the insertion of an earphone and then only performs audio input and output. Therefore, the utilization of such a conventional ear jack interface is limited. Even if any external device can be connected to the 4-pole ear jack interface, this may unfavorably cause great power consumption since a conventional mobile device should always monitor a connection of an external device by continuously detecting the value of an Analog Digital Converter (ADC) received through the ear jack interface.